A spring and strut module typically includes a strut and a spring unit between the brake and knuckle module of a wheel assembly and the frame of the vehicle. The strut incorporates a shock absorber which has a piston reciprocable in a cylinder. The piston has a rod secured to a strut mount which is bolted to the frame of the vehicle. The spring unit includes a spring which resists retraction of the piston. A resilient jounce bumper sleeved on the piston rod also resists retraction of the piston. When the piston retracts, the end of the cylinder sometimes contacts the jounce bumper. This axially compresses the jounce bumper and causes it to expand radially outwardly. Such expansion causes cracking of the jounce bumper and shortens its effective life. What is needed is something to reduce if not altogether eliminate radial expansion of the jounce bumper.
In accordance with the invention, a restraining member preferably in the form of a cup is attached to the piston rod, the cup having a side wall which surrounds the jounce bumper. The wall of the cup confines the jounce bumper and permits only a limited radially outward expansion thereof.
More specifically, the base of the cup is closed by a hardened steel washer which is secured to the side wall of the cup by a press fit. In time, this press fit may loosen. A resilient abutment carried by the strut mount keeps the side wall and washer from separating.
One object of this invention is to provide a spring and strut module having a cup for limiting radial expansion of the jounce bumper, having the foregoing features and capabilities.
Another object is to provide a jounce bumper and cup which are rugged and durable in use and capable of being inexpensively manufactured.
These and other objects features and advantages of the invention will become more apparent as the following description proceeds, especially when considered with the accompanying drawings.